The present invention relates generally to an electric motor assembly and, more particularly, to an electric motor assembly which includes apparatus for mounting a motor control component in the housing of a motor. In one embodiment, a motor assembly includes a one-piece, elastically-resilient mounting apparatus. The mounting apparatus engages at least a portion of a motor control component such that when the apparatus and control component are placed in the motor housing, an outer surface of the mounting apparatus cooperates with an inner surface of the motor housing to ensure that the control component remains locked in the mounting apparatus during motor operation.
Electric motors are manufactured in a variety of types and configurations. The basic components of an induction motor include a stator, an armature or rotor, a shaft, a pair of bearings, end shields, and a motor housing. In addition to these primary motor components, some types and configurations of induction motors include electrical or electronic components which are used to modify operating characteristics for particular applications. Examples of such motors are resistance start, reactor start, capacitor start, permanent split capacitor, and capacitor start-capacitor run motors. These different types of motors are characterized by different speed-torque characteristics, and may be designed to provide different theoretical maximum efficiencies.
For some applications, particularly those where high starting torque is required, part of the windings in a motor may be designed and arranged to serve as auxiliary or starting windings which are energized during initial excitation of the motor, but which are de-energized as the motor comes up to a predetermined speed. De-energization of such windings is often accomplished by a centrifugal switch, or other appropriate device.
In some applications, capacitors, speed control switches, voltage control switches, overload devices, and other electrical components are mounted inside the motor housing with screws to either the motor end flange or to brackets welded inside the motor housing. These mounting methods require the use of either steel brackets welded to the shell with screws used to mount the control device within the brackets, or screws connecting the control device to a separately cast or formed end shield that itself is mounted to the motor housing.
These presently known methods are labor intensive in that both require either welding inside the shell housing or separate casting of a motor end flange to which control components are attached. Furthermore, if a differently-sized component needs to be mounted where a previous component was placed, either the motor housing or the end flange may need to be replaced. A new arrangement for mounting motor control components that eliminates the need for either brackets that are welded in the motor housing or the casting of separate end flanges would be a welcome improvement. A mounting arrangement which reduces the number of parts and the labor associated with mounting motor control components within the motor housing would reduce the total cost of the motor assembly. It is an object of the present invention to provide such an improved mounting arrangement and less costly motor assembly.
According to the present invention, a bracket for mounting a control component in a motor housing is provided. In one embodiment, the bracket includes a one-piece resilient body, elastically movable between a relaxed position and an expanded position and an engaging structure disposed on the body for engaging the control component when the body is in the relaxed position to secure the control component. The engaging structure at least partially disengages the component in the expanded position to allow the component and the body to be separated. The bracket also includes a mounting structure for securing the body to the motor housing such that a surface of the bracket is disposed adjacent and interacts with an inner surface of the housing to prevent deformation of the bracket body thereby locking the component to the bracket.
The one-piece resilient body may be arcuately-shaped and has a top surface and a bottom surface, the body being deformable from the relaxed position to the expanded position. The body is preferably injection-molded from plastic that is thick enough to resist stress fractures caused during flexing from the relaxed position to the expanded position.
The engaging structure is mounted on opposing portions of the body so as to extend in the same direction from the bottom surface thereof. The engaging structure has interior and exterior surfaces that are parallel to one another. Laterally spaced tabs orthogonally extend from the interior surface of the engaging structure so as to define a space into which portions of the control component fit. These tabs may also be diagonally offset. Support surfaces extend from the interior surface of the engaging structure to limit movement of the control component in at least one direction. In one embodiment, the tabs are diagonally offset with one of the tabs being mounted to a portion of the support surface.
The mounting structure includes a flange that is mounted on the top surface of the body. The flange fits into a slot formed in the motor housing. This mounting ensures that the top surface of the body interacts with the inner surface of the housing to prevent deformation of the body to lock the control component within the bracket.
The bracket may also include gussets mounted between the engaging structure and the bottom surface of the body to reduce wobbling of the control component mounted in the bracket. Gussets may also be mounted between the engaging structure and the body, at opposing portions of the body where the engaging structure is attached, to provide strength to the point where the engaging structure is mounted to the body. Finally, gussets may be mounted to the exterior surface of the engaging structure to provide strength thereto when engaging at least a portion of the control component.
The bracket of the present invention may also be molded from thermoplastic so that all the surfaces thereof are all visible from at least one set of two-dimensional perspectives, the set including two different two-dimensional views of the bracket. This allows the bracket to be cast using only two molds, with no mold inserts or subsequent molding or machining steps being required. Thus, tooling expenses associated with the manufacturing process are reduced.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.